Revert "feat: retrieve mip gap from SCIPY solution"

[SteveDiamond]

This reverts commit 6eb5466.

Description

The MIP gap is not available with the interface we are using. Consequently the added tests fail. We didn't notice the regression because of unrelated failures in the CI.

Type of change

• New feature (backwards compatible)
• New feature (breaking API changes)
• Bug fix
• Other (Documentation, CI, ...)

Contribution checklist

• Add our license to new files.
• Check that your code adheres to our coding style.
• Write unittests.
• Run the unittests and check that they’re passing.
• Run the benchmarks to make sure your change doesn’t introduce a regression.

[github-actions]

Benchmarks that have stayed the same:

   before           after         ratio
 [ee17c403]       [f9fa86d0]
      45.9±0s          46.9±0s     1.02  sdp_segfault_1132_benchmark.SDPSegfault1132Benchmark.time_compile_problem
      30.0±0s          30.3±0s     1.01  cvar_benchmark.CVaRBenchmark.time_compile_problem
      8.47±0s          8.49±0s     1.00  optimal_advertising.OptimalAdvertising.time_compile_problem
      9.53±0s          9.53±0s     1.00  huber_regression.HuberRegression.time_compile_problem
      24.1±0s          24.1±0s     1.00  simple_LP_benchmarks.SimpleLPBenchmark.time_compile_problem
      8.72±0s          8.71±0s     1.00  semidefinite_programming.SemidefiniteProgramming.time_compile_problem
      4.12±0s          4.11±0s     1.00  simple_LP_benchmarks.SimpleFullyParametrizedLPBenchmark.time_compile_problem
      11.2±0s          11.2±0s     0.99  svm_l1_regularization.SVMWithL1Regularization.time_compile_problem
      1.87±0s          1.84±0s     0.98  simple_LP_benchmarks.SimpleScalarParametrizedLPBenchmark.time_compile_problem

[sonarcloud]

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0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication